1. Field of the Invention
The invention relates to an oscillating motor employed in particular in the aircraft and vehicle industry.
An oscillating motor of this type consists in general of a stator with a housing having covers on both ends. One or more stator wings are arranged in the housing. A drive shaft which is equipped with an identical number of rotor wings, is supported in the covers. This stator wings and the rotor wings form several chambers having adjustable volumes. The chambers are formed as pressure and discharge chambers, respectively, and are therefore connected with respective supply and the discharge connections.
To provide internal leak-tightness, the pressure chambers and the discharge chambers are separated from each other by a respective frame scaling element which encloses the stator ring and the rotor wing, respectively.
To provide leak-tightness to the outside, a respective annular sealing clement is arranged in the region of the drive shaft between the rotor and each cover. The sealing element is preferably located in the cover.
2. Description of the Related Art
U.S. Pat. No. 3,195,421 describes an oscillating motor which has an annular scaling element in the form of a flexible diagonal sealing ring. The flexible diagonal sealing ring is inserted into an annular groove of the cover and is supported by the wall of the annular groove. Its diagonal sealing edge is oriented against the direction of the pressure towards the circumferential scaling gap located between the end faces of the cover and the rotor wing.
The diagonal scaling ring is subjected to considerable wear due to the frequent change in the relative movement between the diagonal scaling ring affixed in the cover and the rotor wings. This arrangement causes leaks at an early stage of the operation.
An oscillating motor with a similar sealing arrangement is described in U.S. Pat. No. 3,426,654, wherein the diagonal sealing ring is pre-tensioned by a flexible O-ring through a support element. This arrangement attempts a trade-off between leak-tightness and sliding characteristics by carefully dimensioning the force components which act on the diagonal sealing ring.
In this modified sealing arrangement, the sliding and sealing properties are therefore not optimized. Because of the occurring leakage, an additional cylinder seal is required on the journal of the rotor to prevent oil from leaking out. This additional cylinder seal, however, entraps the leaked material and therefore applies in the non-operating state a pressure on the diagonal sealing ring as well as on the rotation bearing, which is adversely affects the start-up characteristics of such an oscillating motor. This arrangement also shortens the service life and limits the possible application for oscillating motors of this type.
Instead of a diagonal scaling ring, a sliding sealing ring may be disposed in the cover to improve the running characteristics.
This modified sealing arrangement, however, is typically rejected because of its poor sealing properties.
Moreover, the sliding sealing ring is in constant contact with the frame sealing element of the rotor and stator wings. Since it is difficult to eliminate a relative movement between the sliding sealing ring and the frame sealing element, the frame sealing element is highly stressed, which results in a short service life.
Is therefore an object to develop a radial oscillating motor of the aforedescribed type which incorporates static sealing points between the rotor and the annular sealing elements.